The present invention relates to a method and device for transferring a fluid sample from a first chamber to a second chamber. The invention also applies to taking a microvolume sample in thermodynamic equilibrium from a chamber and transferring this sample in a pipe.
In particular, the invention relates to sampling a fluid flowing in a pipe at a very low temperature (-20.degree. C. to -100.degree. C.) and high pressure (about 100 bars) and transferring the sample to a line at high temperature (250.degree. C. for example) and low pressure, such as a gas chromatography line.
The invention allows the composition of a fluid flowing in a system to be determined without substantially altering the volume of fluid sampled.
In fact, the difficulty of in-line sampling of a liquid in equilibrium with a gas phase, hence at its bubble point, resides in the fact that the sample must be trapped under strict conditions of thermodynamic equilibrium, then entirely vaporized by heating and/or expansion in the chromatography carrier gas.